Bioreactor Core Facility Introduction and Specific Aims Tissue engineering (TE), i.e., the fabrication of living, 3-dimensional, functional tissue analogs, is a rapidly developing research area that has the potential to revolutionize healthcare. Engineered three-dimensional tissue analogs are intended to replace tissue; in addition, they can serve as research tools to investigate tissue morphogenesis and complex cell-cell interactions. The significance of mass-transport limitations grows rapidly with increasing size of a TE construct; in static culture it can become limiting at construct sizes over a few mm3. At this point, a bioreactor becomes essential to provide an environment in which nutrient supply and waste removal, but also environmental conditions such as pH, temperature, or pressure, can be monitored and controlled. Several bioreactor designs have been commercialized; however, these devices remain quite expensive and complex to operate, and there is little consensus as to what constitutes the best design for a given TE application. Investigators wishing to develop large-scale TE constructs as part of their research program must currently design or purchase their own equipment. Furthermore, TE is now reaching a stage in which the testing of arrays of experimental conditions is becoming critical. Completing such experiments in a timely fashion will require a large number of reactors. This provides a clear rationale for the establishment of a Bioreactor Core Facility, i.e., a laboratory dedicated to providing state-of-the-art technical, instrument, and professional development support, and specialized training of faculty, staff and students. All the projects proposed in this Program Project Grant will make use of a bioreactor at one point or another. Case Western Reserve University does not currently have a formal bioreactor core facility. The PI of this core facility and his co-workers has developed a modular bioreactor system to address the needs of cartilage tissue engineering. The core reactor design is simple, but highly extensible, to allow for a wide range of treatment and monitoring modalities. In addition to the projects detailed in this Program Project proposal, this system has proven itself in the context of other funded projects. It makes technical, scientific and economic sense to centralize all bioreactor-related steps of these projects, from experimental design, to design and construction of bioreactor hardware, to the actual bioreactor operation. Further, this will allow the investigators to focus more of their attention on the basic science questions that are central to their projects. The proposed core facility will emphasize service and core facility research components that are summarized in the following Specific Aims: Specific Aim I: to provide a full-service research bioreactor facility to each PPG project, including: State-of-the-art bioreactor culture facilities for Program Project investigators for routine tissue engineering Technical expertise - this core facility would provide trained and skilled personnel for all bioreactor related operations, thus providing the best possible technical expertise. Assistance in experimental design, based on knowledge of the capabilities and limitations of the system, and development of projectspecific, need-driven extensions to the existing system, will be provided. Specific Aim II: to develop a clinically useful toolset for osteochondral tissue engineering. This research component will focus on developing elements of a system that will ensure clinical scalability and maximize clinical utility. These include process monitoring, and data acquisition and control. Specific aspects to be targeted include: Bioreactor medium homeostasis, by online monitoring of environmental parameters and feedback control through medium flow rate and/or through the use of buffers. MRI protocol development to monitor implant development non-invasively. Implementation of detailed computer modeling of the bioreactor system as a whole, including hydrodynamics and gas/nutrient exchange with the construct. Development of disposable versions of the media-wetted bioreactor components for future clinical applications. The core facility will provide all these services and expertise, freeing the Project Pis to focus on experimental design and result interpretation. The core will be complemented by the Cell, Biomechanics, and Morphology cores outlined elsewhere in this proposal, and will benefit by gathering critical information on the requirements of tissue type investigated, by perfecting computer model templates for different experiment types. These data will then be available from a single source to aid core users in designing their experiments. We therefore anticipate that this facility will become an invaluable resource to a significant number of investigators.